Serum vitamin D levels and influencing factors in elderly patients with stage 3 to 4 chronic kidney disease

Abstract

Objective To investigate serum vitamin D levels and influencing factors in elderly patients with stage 3 to 4 chronic kidney disease (CKD) and to analyze the relationship between vitamin D deficiency and left ventricular hypertrophy (LVH). Methods This study involved 107 elderly outpatients (≥60 years) with stage 3 to 4 CKD who had visited Beijing Hospital between January 2014 and September 2016.We retrospectively analyzed their clinical and laboratory data including gender, age, height, weight, blood pressure, glycosylated hemoglobin, hemoglobin (Hb), albumin, creatinine, lipid, calcium, phosphorus, intact parathyroid hormone (iPTH), high sensitivity C-reactive protein, B-type natriuretic peptide (BNP), 25-OH-D3, and ultrasonic cardiogram.Based on estimated glomerular filtration rate, patients were divided into three groups: the stage 3a CKD group, the stage 3b CKD group, and the stage 4 CKD group.Differences in the parameters between the groups were compared.In addition, 25-OH-D3 levels were used to determine whether the patient had vitamin D deficiency and the left ventricular mass index was used to identify left ventricular hypertrophy (LVH), and the relationship between vitamin D deficiency and LVH was examined. Results Body mass index, body surface area and calcium levels declined while age, phosphorus and BNP levels increased with the development of stage 3a, stage 3b and stage 4 CKD.Mean 25-OH-D3 levels were 22.6 (5.9-58.0) μg/L and 17.5 (10.1-46.3) μg/L for CKD stage 3 and 4 patients, respectively, and the difference between them was statistically significant (Z=-2.121, P=0.033). Compared with patients with no vitamin D deficiency, patients with vitamin D deficiency were more likely to be female (χ2=7.460, P=0.006) and were associated with higher P (Z=-2.090, P=0.037), iPTH (Z=-2.855, P=0.004) and BNP (Z=-3.134, P=0.002), and lower Hb (t=-3.305, P=0.001). The rates of LVH in vitamin D deficient patients and non-vitamin D deficient patients were 8 cases(34.8%)and 12 cases(14.3%), respectively (P=0.035). Conclusions Vitamin D levels show progressive decline as chronic kidney disease advances into later stages.In addition, vitamin D deficiency is more common among female patients and is often accompanied by lower Hb levels, higher BNP levels and higher incidences of calcium-phosphate metabolism disorders and LVH.The results suggest that vitamin D may play an important role in renal anemia, calcium-phosphate metabolism and LVH. Key words: Chronic kidney disease; Vitamin D; Cardiomyopathy, hypertrophic